Winn that simply is not correct. We who hold to Lordship Salvation can know if we are saved. In fact we are the only ones who can. Taking 3 passages and trying to let them stand alone when there are other passages of equal value is not finding the truth. The same writer also said this;
And hereby we do know that we know him, if we keep his commandments.
As in any subject when seeking the truth we dare not take one part to support a belief and deny reject another that deals with the same issue. All those passage put together bring truth. The saved keep the commandments. The saved believe on Jesus and hear His word, the saved love the brethren. Those who teach Lordship salvation hold that all those are necessary to know if we are saved and will be present in every true believer.
So we can and do know, but we base it on what scripture says not feelings like those who teach easy believism. We who are saved hear and believe on Jesus, we love the brethren and we keep the commandments. If a person fails in any of those they cannot know they are saved and in fact they are not saved.
All those are the evidence of the saved not what makes us saved. No one gets saved by coming to Christ only as savior. If they do not want Him as Lord then they remain lost.
No, you cannot have assurance in your system. If you do well today, you might have confidence you are saved. If you do not do well and disobey, you must doubt.
You cannot KNOW you are saved in LS, because you cannot be sure you will persevere. Don't tell me I cannot know this, I can put myself in your shoes and see the logical conclusions. It is bondage.